The Mistress of Science
by FumaFam101
Summary: Lisa noticed her elder siblings were getting very "intimate" with their only brother. Curious, the little scientist set out to find the cause of the intimacy. But she didn't count on getting intimate with Lincoln herself.


**Finally finished this fic. Been writing this fic for a long while on my pastebin but its finally done**

 **Anyway I don't own Loud House blah blah blah.**

Lisa groaned in annoyance, her concentration broken by the loud moans of Leni and Lincoln.

"Looksh like Lincoln is with Leni this time." Sighing, she got up form her desk to check up on her infant sister. "It'sh ashtounding how you canshleep through all this noishe." Lisa said observing the sleeping form of her little sister. She shook her head as she heard Lincoln's moans grew louder.

"I don't undershtand, what could have caused our older siblingsh to have amoroush feelingsh for our only brother." she said pacing back and forth.

Thinking back, it all began a few weeks ago, starting with Luna. Lisa knew they were really close. She noticed Lincoln was there for most of her jam sessions and always praised her, going as far to say that he was her biggest fan. That seemed to have triggered something in Luna to finally take him.

Next was Luan. With cameras set up all around the house for the express purpose of capturing all of Lincoln's embarrassing moments, catching Lincoln and Luna in a very compromising position was bound to happen, and with her obsession for their only brother she definitely wanted in.

When Lori found out, Lisa thought she would put a stop to these incestuous relationships. She was wrong, apparently Lori held strong incestuous feelings for Lincoln as well and with her and Bobby being on "break", she decided to indulge on one of her deepest desires of dominating her brother, and sometimes for Lincoln it wasn't consensual.

Ah Leni, so sweet, so caring, who would've thought she had a dark side. When catching Lori and Lincoln during the act, she insisted that she join, much to Lori's delight. Together the two would ravish their poor brother but unlike Lori, Leni would comfort and pamper Lincoln after their sessions.

While thinking about how all this started, Lisa noticed something, Lincoln spent a lot of time with all of their sister but barley spent any time her. Sure he would help her with experiments from time to time and sure she would cure his illness when he was sick but that's it, they've barley had any time with each other by themselves, just the two of them.

"Hmmm, perhaps by shpending more time with Lincoln, I can find out what caused my siblingsh to have such incestuous feelingsh."

With her mind made up, Lisa grabbed one of her books with the intent of joining her brother on one of his comic book reading sessions.

Lisa headed towards her door but was stopped in her tracks as she heard Lincoln and Leni's moans again. "On shecond thought, perhapsh I should wait a bit." Sighing, Lisa went back to her desk and tried to continue her work while waiting out Lincoln and Leni's intimate session.

 **A few hours later**

Lisa walked down the hallway towards Lincoln's room, noticing that his door was open she peered inside to discover he wasn't there. She decided to check the living room. Making her way downstairs, Lisa spotted her brother on the couch watching his favorite show ARGH.

Lincoln was so into his that he didn't noticed his little sister approaching him. "Hello Lincoln."

Lincoln yelped in surprise then looked over to see his genius sister staring back at him.

"Lisa? Jeez, with you appearing out of no where like that I thought you were Lucy."

Lisa adjusted her glasses. "I apologize for shtartling you Lincoln but with how focused you were, anyone of our sibling could have easily surprise you. Anyway I see that you are enjoying your favorite show dealing with the Paranormal, do you mind if I join you?"

Lincoln smiled "No not at all, come on sit down." he said patting the spot on the couch next to him. Lisa made her way over to the couch and sat on the opposite end.

"How come you're sitting way over there?" Lincoln asked.

"I don't mean to offend, I just prefer my pershonal space."

Lincoln frowned at this. "Aw come on Lisa, the two of us don't get to hang out much besides we're the only one's down here."

Lisa had to admit he did have a point and she it was her idea to spend time with him. With that in mind she crawled over to him.

When she got close enough, Lincoln suddenly picked her up surprising the little scientist.

"L-Lincoln! What are you doing!" Lisa exclaimed, struggling in his hold. Lincoln lied on his back with his sister's head resting on his chest.

"I'm just cuddling with my sister, besides, scientist have said that prolonged physical contact can strengthen a bond between people." Hearing this Lisa stopped her struggling and looked up at her brother, amazed that he knows about that. Laying her head back on his chest.

"It sheems you've been doing your reshearch."

Lincoln chuckled. "I try, this is nice isn't it?" he said running his fingers through her hair.

"I must admit this ish quite enjoyable."

Lisa nuzzled into her brother's chest. Hearing the gentle rhythm of his heart relaxed her and his warmth felt so comforting. Soon her eyelids felt heavy. Closing her eyes, she drifted off to sleep.

Some time later Lisa woke up to find herself alone in the living room. She looked around wondering where Lincoln went until she heard faint moans coming from the kitchen. Making her way over, she peered inside and was shocked at the scene before her.

Lincoln was seated on the counter top with Luan standing in front of him. A look of pleasure adorned his face as Luan kissed and sucked on his neck.

This was the first time Lisa actually witnessed her siblings in an intimate act. Her focus was on Lincoln, The way his body would twitch and the pleasured look on his sent a tingle down her spine. As she heard her brother moan out Luan's name, a thought crossed her mind. 'He should be moaning my name.'

Lisa mentally slapped her self. She left the sibling unnoticed and went upstairs to her room. As she closed the door she thought to herself 'Did I really just think that?' shrugging, she picked out a book to read to get her mind off of the events that transpired.

Over the course of the week, Lincoln and Lisa were nearly inseparable. Weather it was Lincoln helping with her experiments or Lisa joining him in his comic reading sessions, the two were always together and Lincoln loved it.

He loved seeing his reclusive little sister come out of her shell, he also loved how affectionate she is towards him. She even gave him kisses on the cheek much to his delight and the astonishment of their siblings.

Lisa now knows why her eldest sisters are enamored with their only brother. He's so caring, attentive, and always brought out her emotions, not to mention his above average intelligence is also an attractive quality. She even found herself calling him "cute".

She now was completely enamored with Lincoln. Her feelings for him were starting to turn sexual and she planned on acting on her desires soon.

Saturday afternoon at the Loud residence, Lisa was on her way to Lincoln's room to join him for a quiet reading session.

As she passed by Lori and Leni's room, she heard her eldest siblings talking about Lincoln. Curious she walked back towards their room. Noticing that the door was cracked, she peeked to find her two siblings sitting on Leni's bed.

"Like, I'm telling you Lori, Lincoln has a weakness for kissing. It's so cute how he just melts in your arms. Trust me, one good kiss is all it takes for him to submit." Said the fashion expert.

"Oh sweet Leni, when are you going to realize that it's so much more satisfying to just take what you want, to force him to do things, to watch his face change from fear to pleasure as he finally accepts it." Lori said said biting her lip as the cell phone obsessed teen thought about going to Lincoln's and taking him right then and there. Lori was broken out of her fantasy as Leni spoke up.

"But Linky needs to know we really love him! You love him don't you?" Lori felt like she was insulted, how could Leni think she doesn't love Lincoln.

"Of course I love Lincoln, I've wanted him longer than any of you!" Lori exclaimed.

"Then why do you toss aside like he's nothing after you had your fun with him" Leni shot back.

Lori snorted "I do not!"

Sensing an argument, Lisa stopped her eavesdropping and continued on to Lincoln's room, keeping in mind what she heard from Leni.

She knocked on her brother's door and heard his voice acknowledging her to come in. Upon entering his room, Lisa saw her brother laying on his bed playing a handheld game. Her brother took notice and waved her over.

"Hey Lisa, I was just finishing up my game." Lincoln said as he set down his handheld and picked up a latest issue of Ace Savvy. "Ready to relax with some reading?" he asked.

"Of course, I always look forward to our reading sessions." Lisa said as she made her way over to her brother's bed.

Lincoln picked her up and the two siblings snuggled up together and began reading.

While enjoying this moment with her brother, Lisa remembered what she overheard from Leni and Lori. 'Now may be my chance to show Lincoln how I really feel.' she thought.

"Hey Lincoln?" Lisa interrupted. Lincoln stopped reading and looked at his sister as she continued. "I jush want to say that hanging out with you hash been..pretty aweshome." Lisa said as she looked away.

Lincoln couldn't help but chuckle as he saw her blushing face. "Aww I just like spending time with my favorite little scientist." he teased causing Lisa's blush to intensify.

"I-I got you shomething as a token of my appreciation.. B-but you have to closhe your eyesh." Lisa shyly.

smiling Lincoln closed his eyes and waited. He felt her shift around until she was sitting on his stomach. Lincoln wondered what she was doing then he felt a pair of small soft lips upon his. Opening his eye's he was shocked to see his little sister kissing him.

The kiss was awkward and clumsy but that didn't stop Lisa from pouring all her love and passion into it. That's all she needed as she felt Lincoln go limp submitting to her. Lisa was now free to show Lincoln how much she loved him and to act on her desires. Nothing can ruin this moment.. That is until they heard a knock at the door. Breaking the kiss, the sibling looked to see Luna walk into the room.

"Hey dudes I'm not interrupting anything am I?" She asked with a knowing smile. Before Lisa could say anything Luna spoke up again.

"Good cause I was hoping to have some alone time with Linky here if you don't mind." Luna said as she made her way over to the bed.

Lisa looked between the two then sighed. "I don't mind I was just about to leave anyway." She said getting off Lincoln.

Making her way to the door, Lisa looked back at Lincoln. The look on his face seemed like he didn't want her to go. With that Lisa turned around and left the two siblings alone.

Upon entering her and Lily's room, Lisa made her way to her bed. Grabbing her pillow the little scientist shoved her face into it and let out an epic scream of anger. After venting out her frustrations Lisa lied on her back. Staring at the ceiling she muttered three words.  
"Damn you Luna.."

Sometime later, Lisa was walking down the hall. As she passed Lincoln's room, she heard his door open and a voice she didn't want to hear.  
"Hey lil dudette, we need to talk." Luna's voice rang.  
Lisa ignored her sister and kept walking. She was still miffed at her sister for interrupting her special moment with Lincoln. She squeaked when Luna suddenly picked her up.

"Put me down you neanderthal!" Lisa screamed, struggling against her sister.

"Now that's no way to talk to your big sister, besides what I have to say involves you and Lincoln."

Lisa stopped struggling and sighed. "Alright, I'll listen to what you have to say. Just put me down."

Luna set he little sister down. "C'mon lets got to your room."

The two siblings walked back to Lisa's room. Lisa sat on her bed as Luna closed the door behind her.  
"Alright Luna, talk."

"I know what you were going to do with Lincoln." Lisa wasn't shocked at this. Luna had caught them in a compromising position.

"Didn't know four year olds could get like that, let alone you. Anyways, I'm sorry for interrupting your moment. It's been a while since I had some alone time with Lincoln."

Lisa could see the see the sincerity in her eyes. "It's alright, Luna. You don't have to apologize. I am starting to realize that despite my best efforts, Our dear male sibling would have rejected me." Lisa lamented "I mean look at me. My tiny body would not be able to handle Lincoln's size."

Luna chuckled. "C'mon Lise, I thought you were smarter than this."

"What's that supposed to mean?" Lisa demanded.

"What I mean is you're Lisa Loud! Your're the smartest person I know. Always doing crazy experiments and crazy making serums. I'm sure you could make something that will give you the body of an eighteen year old."

Lisa's eyes widened as she processed what Luna suggested. "Of course, how could I be so stupid! I can create a serum that will increase my age." Lisa gave Luna a hug. "Thank you for giving me this wonderful idea and reminding me that I am a scientist."  
Luna patted her sister's head. "No problem little sis."

After Luna left the room, Lisa got to work on the serum. She had to make sure everything was perfect. This wasn't just for her own benefit, but for Lincoln's as well.

"Finally! After three long hours of calculations and mixing the right chemicals I've finally produced an aging serum."

With the serum in hand, Lisa went to Luna and Luan's room. Both sisters agreed to help Lisa if the serum went wrong.

Knocking on the door, she was greeted to Luna's smiling face. "So that's the aging stuff." Luna asked eyeing the vile of blue liquid.

"Yesh it is." Lisa responded as she walked into the room. "If my calculations are correct this serum should give me the body of a seventeen year old." She looked nervous. "I just hope this works." Lisa fretted.

Luan made her way over to her little sister and gave her a reassuring hug. "Of course it'll work Lisa, we know how much you love Lincoln and we know how hard you worked on this" Luan comforted. Luna also joined the group hug.

Lisa felt happiness knowing that her sisters supported her endeavors. "Thank you girlsh." Lisa hummed.  
Pulling away from the loving embrace, Lisa took one last look at the vile and sighed. "For Lincoln." She whispered as she gulped down the blue liquid.

After a few seconds Lisa's body turned into dense vapor.

Luna and Luan panicked but then noticed that the vapor began to enlarge and take on a human shape.

when the vapor cleared, both sister were in shock and awe at what they witnessed.

"Woah.." was all Luan could saw  
Luna smirked. "Lori is gonna be so jealous when Lisa gets older." Luna turned to her sister. "Alright Luan time to prepare our lil-big sister for Lincoln."  
Luan smiled as she bought out her box of sex toys.

Later that night, Lincoln made his way up to his room. He planned on reading a few comics before going to bed. When he opened his bedroom door and turned on the light he was greeted with a beautiful sight. There, laying on his bed was a very curvy naked woman staring back at him. He stared in awe at her long brown hair, her thick thighs, her big perky breast, those full plump lips, and her round glasse- wait glasses?

"L-Lisa?" Lincoln marveled

"Hello, dear sibling." Lisa said in a sultry tone.

Lincoln couldn't believe it. This gorgeous woman was his little scientist. He was broken out of his daze as he heard her lovely voice again.

"Close the door." She commanded. Lincoln obeyed and shut the door.

"Disrobe yourself." again Lincoln complied and took off all of his clothes.

Lisa sat up. "Now..." she extended her arms and spread her legs. "Come into my sweet embrace."

The boy wasted no time as he threw himself in his sister's arms, nuzzling her breast.

Lisa couldn't help but giggle at the display. A week ago she was being cradled in her brother's arms, now its the other way around.

Tracing her hand down his cheek, she cupped his chin. The boy looked up at her, the two stared lovingly into each others eyes until Lisa leaned down to capture his lips with hers.

Lincoln felt a shiver go down his spine when he felt his sister's tongue invade his mouth. He couldn't help but moan as her tongue dominated his.  
Lisa loved how her brother melted into the kiss fully submitting to her. 'Leni was right.' she thought as she continued to dominate his mouth.  
The kiss went on for a few more minutes before Lisa pulled away, a thin trail of saliva still connecting the two siblings.

"I assume my kiss was more than satisfactory?" Lisa smirked.

"W-Where did you learn how to kiss like that?" Lincoln asked in a daze.

"Our siblings, Luna and Luan taught me. They taught me a lot of things to please you." She kissed his forehead. "I'm not doing this only for myself but for you as well. I love you big brother."

Lincoln stared up at her in awe and smiled. "I love yo-" Before he could finish, Lincoln was suddenly thrown onto the bed and was pinned by his big-little sister. The boy shivered in both fear and excitement as his sister loomed over him. Lincoln noticed she was giving him the same grin that she's given his tutor long ago. "Oh god what are you gonna do to me?" Lincoln whimpered.

Lisa leaned in close, her breath tickling his ear. "I'm going to claim what's mine." Lisa purred as she proceeded suck on his neck causing the boy to let out a cute moan. Lisa giggled, she liked that, she wanted to hear more sounds from him. She gently bit down, loving the surprised squeal from her brother. She pulled back leaving a lovely little love bite.

"Sorry girls but this boy is mine now." Lisa smirked as she inspected her brother. He was panting, his face flush with lust and excitement.  
'This is so exhilarating.' Lisa thought biting her lip. She crawled back until she was facing his penis. It stood hard and firm at seven inches. 'This is the real thing.' Lisa thought gleefully. She gently grasp his dick, giggling as she heard him gasp.

Lisa looked up at Lincoln to find him biting his lip staring back at her. His eyes pleading for her to take him in her mouth.

Not wanting to keep her brother waiting, Lisa ran her tongue along the tip before completely taking him into her warm mouth.

Lincoln threw his head back and howled as his sister started to fellate him, her tongue enveloping his head making him scream her name.

"Oh god Lisa!" Lincoln gasped. His sister moaned in response. She took his hands, interlocking their fingers together.

The boy looked down at his sister to find her staring back at him. His sister began to slowly move her head upwards, her tongue running along the underside of his dick, suckling gently before releasing it with an audible pop.

She gave Lincoln a loving smile before taking him all the way into her mouth effectively deep throating the boy.

'God, Luna and Luan taught her too well!' Lincoln thought. He began panting, squeezing her hand as he felt himself get closer to climax.

"Lisaaahhh!" Lincoln moaned arching his back ready to release into his sister's waiting mouth.

Lisa suddenly pulled back, holding him tightly by the base of his shaft preventing him from cumming.

She couldn't help but laugh as her brother thrust his hips, desperately trying to cum.

The boy looked up at her. "Wh-why did you stop? I was so close." Lincoln whimpered.

Lisa smiled maliciously at him. "Because my dear sibling, where would be the fun in that. Besides edging will result in a much more powerful orgasm."

She leaned in close, licking the tip of his nose. "Wouldn't you like that, Linky?" Lisa purred.

The boy nodded eagerly, making Lisa smile. "Good boy." She sat up, grabbing his ankles, her pussy hovering over his tip.

"Wh- what kind of position is this?" Lincoln asked confused but even more aroused.

"Why this dear sibling is know as the Amazon Press. Honestly I'm surprised Lori hasn't done this to you yet." She then smiled. "But I am glad that I will be the first to try this position on you."

With Lisa plunged down on his cock, taking it all in one go.  
Shivers went down Lisa's spine. She felt so warm, so filled. 'This feels so much better than those toys Luan has.' Lisa thought.  
Lisa slowly started rocking her hips back and forth, loving how his cock was hitting all the right spots. She looked down at her sibling finding him looking back at her, his face wracked with pleasure.

"You're so perfect." Lisa cooed as she started to piston herself on his dick.

Lincoln gripped his sheets, crying out her name as she picked up speed.

That's what Lisa wanted to hear, Lincoln screaming her name in ecstasy. She loved the dominance this position afforded her, she loved the expressions and cries coming from her brother, she loved everything about this moment. But it was all coming to a close as she felt her brother start twitching inside her.

Not wanting this beautiful moment to end, Lisa suddenly lifted herself off before Lincoln could cum, watching his dick twitch violently before finally stopping.

The pained whine coming from her brother tugged at Lisa's heartstrings. Leaning down, she kissed his forehead.

"Do not worry my dear sibling." Lisa whispered huskily in his ear. "Your climax will arrive soon and I promise that it'll be the best you've ever had." With that said she lowered herself back onto Lincoln's dick.

Lisa slowly pumped her hips, too slow for Lincoln's liking. The boy couldn't lie, he loved every minute of it but the edging was driving him crazy.

"Lisaahh... Please let me cuummhhh." Lincoln moaned, his legs barley wrapping around her hips as he tried to thrust his hips upward.

Lisa giggled at his efforts. She would love to filled with his cum, but she wanted to tease him a little bit longer.

"Who's your Mistress of Science." Lisa whispered in his ear as she sped up.

"You are!" Lincoln moaned out loud.

Gripping his hair, Lisa tilted his head up, forcing him to look at her. "Who's the smartest and sexiest woman you know!" Lisa moaned along with Lincoln, her own climax approaching.

Lincoln wrapped his arms around her neck. "You are!" The boy screamed.

"Cum for me Lincoln, cum for your Mistress!" Lisa exclaimed as she kissed her brother deeply, shoving her tongue down his throat.

Lincoln hugged his sister tight to his body, moaning loudly into her mouth as he came hard shooting jet after jet of cum, filling her to the brim.

Feeling Lincoln cum inside her set off her own climax, gripping her brother's hair tighter as she too moaned into his mouth.

Both siblings held each other tight, their bodies convulsing as they both rode out their intense orgasms together.

After what felt like house their orgasm started to die down. Lisa pulled back from the kiss, both siblings stared at each other, smiling as they bask in the afterglow.

With her remaining strength, Lisa rolled the both of them over. She stroked Lincoln's hair, sighing happily as she felt him planting soft kisses on her neck.

"The feeling of winning all the prizes and rewards I've earned in the name of science does not compare to this." Lisa kissed his hair.

"You're a wonderful big brother, Lincoln." Lisa praised.

"And you're an amazing sister, my lit-big scientist." Lincoln responded in kind.

They both shared a quiet laugh before letting sleep take them to dreamland.

In the vents, Lucy spied on their happy moment wondering if she needed to use that serum on herself. Sighing at the sleeping couple she smiled. "Soon, Lincoln.. Soon."


End file.
